What this snippet does
When targeting ES5, extending built-in classes like Error can break instanceof unless you manually set the prototype.
Expected output
false
Why practise typing this
Typing error handling code builds muscle memory for the symbols and indentation TypeScript uses most, which prose-based typing tests never cover. DevType measures your words per minute and accuracy on this snippet and tracks the individual characters you mistype, so later lessons can target them.
More TypeScript practice
- Extending the base Error classError Handling · intermediate
- Adding contextual data to custom errorsError Handling · intermediate
- Catch clause typed as unknownError Handling · intermediate
- Using instanceof to narrow caught errorsError Handling · intermediate
- Accessing message property on unknown errorError Handling · intermediate
- Throwing a string literalError Handling · intermediate